Mandolin attachment for pianos



Jan. 18, 1927.

w. G. B ETZ MANDOLIN ATTACHMENT FOR PIANOS Filed Jan. 31 1921 Patented Jan. 18, 1927.

UNITED STATES PATENT OFFlCE.

WILLIAM G. BETZ, OF HAMMOND, INDIANA. ASSIGNOR TO STRAUBE PIANO COMLANY, OF HAMMOND, INDIANA.

MANDOLIN ATTACHMENT FOR 1 152111052.

Application filed January 31, 1921.

My invention relates to mandolin attachments for pianos, that is devices of that character in which the tones of a piano may be changed so as to produce a tone closely resembling that of the harp.

Hereto'fore in a device of this character in which flexibly supported buttons are moved into operative relation with the keys and strings by means of a button supporting rail secured by pivot frames attached to its ends, the devices frequently got out of alignment or when operated one end would lag behind the other and thereby produce an uneven operation of the device. That is, the rail which supports the modulating buttons, due to being supported at its ends only upon pivotally mounted brackets and restrained by a spring tension applied at one end, would easily become pulled out of alignment because oi? the operating and restraining strains being applied at different points along the rail.

In order to overcome these difficulties I have provided an improved structure in which a rigid bar extends across the face of the piano strings, this bar or shaft being nvotally supported at its ends and carrying a. rail which supports tone changing buttons carried by a flexible supporting means which is attached to the rail. The main bar is then oscillated on its pivots so as to move the rail and thereby the tone changing buttons into operative position before the strings. By this construction the entire arrangementis rigid and the button supporting rail maintained in permanent alignment with the pivots or bearings by which it is supported, thus preventing improper alignment of the tone modulating buttons, strings and hanr mers.

For a better understanding of my invention reference is to be had to the accompanying drawing in which- Fig. 1 is a transverse section through a portion of a piano, showing my improved tone modulator supported therein;

Fig. 2 is a face view of a portion of a piano and a portion of the tone modulating device; and

Fig. 3 is a plan view of a portionof the tone modulator enlarged somewhat so as to more clearly show the parts.

Referring now more in detail to the construction as illustrated, I provide a rigid bar or shaft 5 which is pivotally supported is provided extending across the face of the 1 attached to the operating bar 5 by n'ieans i a suitable number of brackets 10. These lJl clzets are suitably secured at one end to the bar 5, preferably by being instrings an serted in a hole therein. said brackets being slotted at their free ends 11 so that the rail may be adjustably attached to the brackets 10 by screws 12. Thus the rail 9 may be adjusted relatively to the strings 8, that is moved it rv.*ardly or baclzwardly as required. T his rail 9 carries a flexible strip 13, preferably of a suitable cloth which is slotted at 1.4: so as to provide tongues corresponding to the strings, and spaced so that there is one strip before each of strings. At the lower end oi. each tongue 15 is a tone modulatin button 16 made of a hard substance prelerabiy fibre and suitably attached to the tongue 15, pre'l rably by being glued. thereto.

in order to hold the buttons normally out of operative relation with the strings 8 and hanuners 17, the button operating mechanism is normally under tension of a spring 18 which is secured at one end to a stationary part oi the piano, as for instance the case, and its other end to the shaft or bar 5 by means of a hook-shaped arm 19 suitably secured to the bar 5 preferably by being screwed into the wood.

In order to operate the mechanism a suitable rod 19 is provided being preferably attached to one of the brackets 10 and extending downwardly to where it may be connected to an actuated bellows 20 controlled from the usual button 21 at the key-board or the rod 19 may extend downwardly to be actuated by a treadle (not shown).

The tone modulating buttons 16 are normally positioned by attaching the rail 9 so that when the bar 5 is rotated, the button 16 is brought slightly below the point of impact of the hammer 17 as indicated by the dotted lines in Figure 1. Also the button in its operative position should be attached so as to hang slightly free of the strings 8,

about three-sixteenths or one-fourth inch being a suitable distance. This. of course, may vary according to the tone desired and the action used.

In the operation of the device the actuating rod 19 is moved downwardly thereby rotating the shaft 5 about its axis and thus moving the rail and tone modulating buttons downwardly into the position indicated by the dotted lines in 1. The hamn'iers 17 when now actuated strike the cloth tongue 15 slightly above the top of the button 16 but due. to the inertia of the button 16 the hammer 1T strikes the string 8 with the tongue interposed practically the same instantthat the button 16 hits. T he ensuing retractive movement ot the hammer 11' then permits the intermediate portion of the tongue 15 to follow the hammer 1'? "for a shortperiod so that the button 16 leaves the strings S slightly a'tter the hammer struck portion of the tongue has disene d from the string. This striking and retracting peration has the eilect of producing a ditjlerent vibratory eitect upon the strings so that the tone produced is more in the nature of that ordinarily produced by a harp.

It will be understood, of course, that the tone modulating device may be moved into and out of operative relation with the strings and hammers as desired, IQSPOlltllTlg very quickly to the manual or pnemnatic control.

By means of my improved construction the supporting rail 9 ma;' be readily adjusted to a proper position and when once set is very effectively maintained in adjustment. Also due to the method of assembling and supporting the rail and shaft 5, the buttons are more effectively held in proper alignment and the operating and restraining strains upon the mechanism do not pull the parts out of alignment as heretofore.

What I claim is:

1. In a tone changing device for pianos having strings and hammers, tone changing buttons 'ith flexible means for su:-:pe11ding them adjacent the strings normally above the hammers, said buttons and flexible suspending means being freely movable between the hammers and strings and the hanni'iers being unobstructed in their travel to strike the strings with the flexible suspending means only interposed, and means for moving the buttons sufiiciently below the han'nner strils ing point on the strings and sutliciently' away from them whereby the hammers when operated will strike the flexible supportii'ig means suflieiently above the buttons and carry it to the strings so that the buttons and flexible support where struck by the hammer will strike the strings sniliistantially simultaneously.

2. In atone changing device for pianos, a tone changing button supporting rail for extending across the taco ot the piano strings, tone changing buttons suspended from the rail, a sl att parallel to the rail and brackets connec ing the rail to the rha'lt to provide a rectangular frame, supports for the frame so as to permit rotating the frame on its pivots for lowering and raising; the rail and buttons, and means for rotating the frame on its pivots to lower and ra se the rail by applying an operating torque to the shaft without applying the strain of the operating torque to the rail.

In witness whereof, I, hereunto my name this 29th day of Dec. A

subsc ri he 1)., lilitl. 

